<template>
  <div class="s-canvas">
    <canvas id="s-canvas" :width="contentWidth" :height="contentHeight"></canvas>
  </div>
</template>
<script>
  export default {
    name: "SIdentify",
    props: {
      identifyCode: {
        type: String,
        default: "1234"
      },
      fontSizeMin: {
        type: Number,
        default: 25
      },
      fontSizeMax: {
        type: Number,
        default: 30
      },
      backgroundColorMin: {
        type: Number,
        default: 255
      },
      backgroundColorMax: {
        type: Number,
        default: 255
      },
      colorMin: {
        type: Number,
        default: 0
      },
      colorMax: {
        type: Number,
        default: 160
      },
      lineColorMin: {
        type: Number,
        default: 100
      },
      lineColorMax: {
        type: Number,
        default: 255
      },
      dotColorMin: {
        type: Number,
        default: 0
      },
      dotColorMax: {
        type: Number,
        default: 255
      },
      contentWidth: {
        type: Number,
        default: 112
      },
      contentHeight: {
        type: Number,
        default: 31
      }
    },
    methods: {
      // 生成一个随机数
      randomNum(min, max) {
        return Math.floor(Math.random() * (max - min) + min);
      },
      // 生成一个随机的颜色
      randomColor(min, max) {
        const r = this.randomNum(min, max);
        const g = this.randomNum(min, max);
        const b = this.randomNum(min, max);
        return "rgb(" + r + "," + g + "," + b + ")";
      },
      drawPic() {
        const canvas = document.getElementById("s-canvas");
        const ctx = canvas.getContext("2d");
        ctx.textBaseline = "bottom";
        // 绘制背景
        ctx.fillStyle = this.randomColor(this.backgroundColorMin, this.backgroundColorMax);
        ctx.fillRect(0, 0, this.contentWidth, this.contentHeight);
        // 绘制文字
        for (let i = 0; i < this.identifyCode.length; i++) {
          this.drawText(ctx, this.identifyCode[i], i);
        }
        this.drawLine(ctx);
        this.drawDot(ctx);
      },
      drawText(ctx, txt, i) {
        ctx.fillStyle = this.randomColor(this.colorMin, this.colorMax);
        ctx.font = this.randomNum(this.fontSizeMin, this.fontSizeMax) + "px SimHei";
        const x = (i + 1) * (this.contentWidth / (this.identifyCode.length + 1));
        const y = this.randomNum(this.fontSizeMax, this.contentHeight - 5);
        var deg = this.randomNum(-45, 45);
        // 修改坐标原点和旋转角度
        ctx.translate(x, y);
        ctx.rotate(deg * Math.PI / 180);
        ctx.fillText(txt, 0, 0);
        // 恢复坐标原点和旋转角度
        ctx.rotate(-deg * Math.PI / 180);
        ctx.translate(-x, -y);
      },
      drawLine(ctx) {
        // 绘制干扰线
        for (let i = 0; i < 5; i++) {
          ctx.strokeStyle = this.randomColor(this.lineColorMin, this.lineColorMax);
          ctx.beginPath();
          ctx.moveTo(this.randomNum(0, this.contentWidth), this.randomNum(0, this.contentHeight));
          ctx.lineTo(this.randomNum(0, this.contentWidth), this.randomNum(0, this.contentHeight));
          ctx.stroke();
        }
      },
      drawDot(ctx) {
        // 绘制干扰点
        for (let i = 0; i < 80; i++) {
          ctx.fillStyle = this.randomColor(0, 255);
          ctx.beginPath();
          ctx.arc(this.randomNum(0, this.contentWidth), this.randomNum(0, this.contentHeight), 1, 0, 2 * Math.PI);
          ctx.fill();
        }
      }
    },
    watch: {
      identifyCode() {
        this.drawPic();
      }
    },
    mounted() {
      this.drawPic();
    }
  };
</script>
<style scoped>
  .s-canvas {
    height: 38px;

  }
  .s-canvas canvas{
    margin-top: 1px;
    margin-left: 8px;
  }
</style>
